Is secondhand smoke from vapor of e-cigarettes dangerous?Sharon Cummins, PhD, assistant professor, Department of Family Medicine and Public Health, UC San Diego School of Medicine

When e-cigarettes first came on the market, there were claims made that the smoke from an e-cigarette is "just harmless water vapor." We now know that this is not true. The vapor is actually an aerosol that contains nicotine and other compounds that could be dangerous to inhale.

The main issue is that the manufacture of e-cigarettes is still largely unregulated. As a result, we don't really know what is in them. Some e-cigarette liquid has been found to contain heavy metals, such as lead. Most also contain flavorings that, when heated, could be harmful. While the aerosol is likely to be less dangerous than cigarette smoke, it is not completely safe. It is best to avoid secondhand exposure when possible, especially among young children.

What is the difference between a heart attack and heartburn?Lori Daniels, MD, cardiologist, UC San Diego Health

The symptoms of a heart attack can sometimes be confused with those of heartburn since both may cause an uncomfortable sensation in the chest. I have had patients diagnose themselves (or sometimes get diagnosed by clinicians) with heartburn for weeks or even months, only to later find out that their chest discomfort was due to reduced blood flow to their hearts, also known as angina.

Both heartburn and heart attacks can present with chest discomfort. In heartburn, the symptoms are typically a sharp or burning sensation in mid-chest that is worse after a large meal (especially a spicy or fatty one) or after lying down. It can last several hours and may improve after taking an antacid.

In contrast, chest discomfort that is due to angina or a heart attack is generally worse with exertion and better with rest. Although classically described as a vice-like pressure or tightness in the chest, or like “an elephant sitting on my chest," the chest discomfort from angina might instead be burning in nature in some people. It might radiate to the neck, jaw or left shoulder or arm. In some cases, it may be associated with sweating, nausea, shortness of breath or fatigue. Women, elderly individuals and those with longstanding diabetes may experience atypical symptoms with heart attacks and sometimes may have no chest symptoms at all.

The cause of your chest discomfort is more likely to be related to your heart if you have risk factors for heart disease, including diabetes, smoking, high blood pressure, elevated cholesterol, obesity and/or a family history of heart attacks. Heart attacks and angina are also more common the older you are, especially in men over the age of 45 and women over the age of 55.

There are exceptions to the above rules of thumb. Occasionally, chest pain that is due to heart problems might feel better temporarily after taking an antacid. Angina can also sometimes occur after a fatty meal due to some blood flow getting diverted to the stomach and away from the heart. Therefore, if you are having significant chest discomfort that does not pass within several minutes and that feels different from your typical heartburn, or especially if you have never had heartburn before, it is generally better to play it safe and seek emergent medical input by calling 9-1-1 and/or coming to the emergency department for further evaluation.

Is it possible to acquire an infection while sampling makeup at a store?Arisa Ortiz, MD, director of Laser and Cosmetic Dermatology, UC San Diego Health

I would think twice next time you want to test makeup at a department store. Choosing the perfect lipstick color may be detrimental to your health. Makeup testers can harbor many strains of bacteria, viral herpes which causes “cold sores,” and even yeast. Researchers have found staph, strep and even E. coli bacteria on makeup counter testers. Using makeup with these bacteria can cause infections, rashes or “pink eye.”

The FDA recommends against sharing makeup, and using retail store makeup testers is like sharing with a few thousand of your friends. If you must test a product first, make sure to use a tester in a closed dispenser, like a pump or tube that squeezes rather than a jar that people must dip their finger into. You can also sterilize the makeup tester using an alcohol swab prior to application. Make sure to apply with a disposable applicator rather than a reusable brush. If you do not see one at first, it is always a good idea to ask, because these are sometimes kept behind the counter. Another idea would be to test a lipstick on the back of your hand rather than on your lips, which are most susceptible to infection. If you want to play it safe, just purchase the makeup without testing, and if it does not work out, most stores have a return policy.